Private Lives of Island View Beach`s Western Black Widows
Transcription
Private Lives of Island View Beach`s Western Black Widows
Volunteers Spring Newsletter 2014 | Capital Regional District Feature: Western Black Widows VIP Profile: Claire Buchanan In Parks Staff Profile: George Golmer Volunteer & Park Updates Private Lives of Island View Beach’s Western Black Widows V By Catherine Scott isitors to Island View Beach may be surprised to learn that western black widows are the predominant web-building spiders in the area. Most people will never see them, as they are nocturnal, shy, and unaggressive. During the day they stay hidden under logs, but after dark they come out onto their webs and wait for prey to blunder into their silken traps. A female western black widow hangs from her web during the night, waiting for her next meal, or a courting male. The capture web extends from a silken retreat under the driftwood, where she shelters during the day. Belying their name, females of this species rarely consume males, who are much smaller than their typical prey. Photo Sean McCann Regional Parks 490 Atkins Avenue Victoria, BC V9B 2Z8 T: 250.478.3344 parksvolunteer@crd.bc.ca www.crd.bc.ca/parks Male western black widows are variable in colour and much smaller than the familiar black females. Once they mature, males abandon their webs to wander the dunes in search of mates. My research examines the sexual communication system of these beautiful, mysterious spiders. Continued page 2 Top: The diminutive, colourful male western black widow spends his adult life wandering the dunes, searching for females. This male has climbed up onto the vegetation, perhaps to get a ‘whiff’ of a female’s web on the wind. Right: This cage, with an intact female’s web inside, was surrounded with sticky strips to capture males that were attracted to the female’s silk pheromones. At least 15 spiders can be seen trapped outside this cage. Female black widows build large three-dimensional cobwebs, which not only ensnare prey, but are also used for communication. Pheromones (chemical signalling molecules) on the silk allow males to ‘sniff out’ potential mates. These chemicals can tell the male whether the female is well fed or starving (indicating the risk of cannibalism), and if she has previously mated. This information may help him decide whether to enter a web and begin his courtship display, or move on in search of a more receptive female. does in fact decrease the attractiveness of a female’s web. It’s not yet clear if this is a result of suppressing the female’s signals, the addition of male silk pheromones, or both, but we now understand more about the function of this behaviour. With web-reduction, the male manipulates the female’s attractive pheromone signals, reducing the chances of other males finding her web and competing for her affections. Next time you’re out at Island View Beach, take a closer look at the woody habitat that is home to a whole host of species including the black widows. You might spot a tangled web extending from under a log onto the sand or nearby vegetation. This sophisticated structure acts as both an effective trap for prey and an aromatic advertisement for mates. Below the driftwood, elegant spiders play a deadly but vital role in the diverse coastal dune ecosystem. ‘Web-reduction’ is a curious part of the male’s courtship display, which includes sending vibratory signals through the web to the female. Soon after a male enters a female’s web he often begins dismantling it, cutting and bundling up large sections, then wrapping them up with his own silk. We wanted to find out if web-reduction behaviour decreases the attractiveness of a female’s web. The shrunken surface area of the web could minimize the release of attractive pheromones, or the added male’s silk might carry its own pheromones that are repellent to other males. Catherine Scott is a MSc student at Simon Fraser University. She and her colleagues are researching the western black widow at Island View Beach and on the traditional lands of the Tsawout First Nation with their generous permission and support. Photos courtesy Sean McCann. Find out more about the research on Catherine’s blog at spiderbytes.org. To study the function of web-reduction, we ran an experiment on the beach. We set out cages containing both intact and malereduced females’ webs and surrounded them with sticky traps to capture males that were attracted to the scent of the silk. In a single night we captured more than 200 mate-searching males outside the cages. We caught far fewer spiders with reduced webs than intact webs, indicating that web-reduction CRD Volunteers in Parks Spring 2014 Newsletter -2- C VIP Profile laire Buchanan is a Park Naturalist at Witty’s Lagoon Regional Park in Metchosin. She has volunteered with the CRD since 2012. What do you enjoy most about volunteering? My favorite part of volunteering with Regional Parks is seeing the excitement on visitors’ faces when they come into the nature house after seeing something really neat in the park. I love hearing their stories. I think it’s important to have places, like the nature house, where people can share their interest in the natural environment. What is your favourite volunteer experience or memory? My favorite memory of volunteering happened on a rainy day. The nature house had been very quiet all day until a mother and her daughter came in. They were really interested in the natural environment of the park because they were new to the area, and wanted to learn more about their new home. We spent an hour going through the showcase and all the drawers in the nature house examining and learning about all the different species you could find in Witty’s Lagoon. It was a great experience to learn and share together. G Staff Profile eorge Golmer is a Parks Operations Supervisor for Regional Trails and the Gulf Islands. Where have you worked previously? Starting at 15 years old I was employed as a lifeguard at Elk/ Beaver Lake Park for (then) Saanich Parks. I did this for several summers while going to school. I also volunteered with Saanich conducting Colquitz Creek cleanups and did trails and grounds maintenance at both Elk/Beaver and Cedar Hill Golf Course. In 1976 I started my career with CRD Parks as their Head Lifeguard and have since worked in every park, in almost every capacity. While working for CRD Parks I have experienced more opportunities and challenges than I could ever have imagined. What is your favourite park? Thetis Lake because of its natural beauty, proximity to the city and size. This park is amazing, large enough that you can get lost and close enough that you can access WiFi. Where were you born? Tell us a bit about yourself. After WW2 ended my father ended his naval career in the dockyards of Victoria. He got off the ship during the winter months and didn’t want to return to Saskatchewan to shovel snow, so he stayed. I was born in Victoria and although I have done a considerable amount of travelling, I think he made the right call and I have never wanted to live anywhere else. I am currently in my fourth year at the University of Victoria. I am studying geography and environmental studies. I have always loved spending time outdoors and hope to dedicate my career to ensuring that we will always have outdoor spaces to enjoy. Besides volunteering I love to spend my spare time kayaking, hiking, and reading. My wife Eva and I have two perfect sons. They both agree with their grandfather and live here. We have enjoyed camping and hiking at many parks across Canada. Naturally when I retire I plan to visit more of our national parks. Don’t get me wrong, sometimes I go to Vegas. What is your favourite park? My favorite Regional Park is East Sooke. I love the endless coastline and trails in the park. It is a great place to explore! CRD Volunteers in Parks Spring 2014 Newsletter Tell us a bit about yourself. -3- Volunteer & Park Updates New Volunteers Welcomed On Feb. 20, nine new Park Stewards were added to our volunteer team. Below is a list of the new Park Stewards and their assigned parks. • Eric Addleman – Mt. Wells • Chantelle Clark – Elk/Beaver Lake • Alison Harle – East Sooke • Steven Leclerc- Island View Beach • Jeni Luther – Matheson Lake • Dylan Sayer – Island View Beach • Julie Thomson – Bear Hill • Lara Wear – Bear Hill • Eldred Williams – Mill Hill 2013 Park Visitation Statistics Regional Parks actively monitors visitation levels throughout the regional parks system. 57 counters are placed in strategic locations to capture visitation data. This data assists Regional Parks in developing park management plans and operational strategies, including the identification of facility development needs. When compared to 2012, visitation increased by 6.6% or 382,947. Regional Park / Trail Albert Head Lagoon 2013 Visits 57,977 Brooks Point 5,822 Coles Bay 27,922 East Sooke 135,878 Devonian 50,301 Elk/Beaver Lake 1,484,164 Galloping Goose Regional Trail 1,825,947 Francis/King 93,807 Gonzales Hill 40,515 Horth Hill 63,906 Island View Beach 335,160 Jordan River (Sandcut Beach) 11,767 Lochside Regional Trail 1,099,396 Lone Tree Hill 5,729 Matheson Lake 49,784 Mill Hill 34,727 Mount Parke 5,430 Mount Wells 30,837 Mount Work 154,036 Sooke Potholes 104,178 Witty’s Lagoon 85,123 Sea to Sea (Harbourview) 31,106 Thetis Lake Total Volunteer Naturalist and Volunteer Trail Ambassador Recruitment Starting in April, we will be recruiting for year-round Volunteer Naturalists at the Nature Centres at Francis/King and Witty’s Lagoon regional parks and Summer Volunteer Naturalists at Elk/Beaver Lake and Witty’s Lagoon regional parks. As well, we will be recruiting more Volunteer Trail Ambassadors. Please pass this information on to any folks who you think might be interested and direct them to Colleen Long: clong@ crd.bc.ca, 250.360.3329 or crd.bc.ca/parks further details. CRD Volunteers in Parks Spring 2014 Newsletter 429,934 6,163,446 Witty’s Lagoon Trail Closure The trail and staircase at Witty’s Lagoon Regional Park, which leads to the main beach off Witty Beach Road, is closed for public safety. The clay hillside on which the stairs are built is prone to slumping, causing slope instability. The bank’s instability results from natural processes that feed the spit, beach and intertidal features. As a result of a February 2014 engineering report, closure of the stairs was recommended. Visitors can still access the beach from the main parking lot off Metchosin Road. The beach is also accessible from Tower Point during low tide. -4-